1. Field
The present disclosure relates to microfluidic apparatuses, and more particularly, to microfluidic apparatuses for separating a target cell from a biological sample.
2. Description of the Related Art
Most cancer-related deaths are due to metastasis to a tissue or organ located far from a point where a tumor originates. Thus, discovery of a metastasis at an early stage is a critical factor that determines survival probability. Early detection and monitoring development of a tumor are deemed as key factors in successfully treating cancer patients. A histopathology-based diagnosis is used to detect cancer. The histopathology-based diagnosis is a technique for diagnosing a cancer using a tissue sample obtained from a biopsy specimen. However, a biopsy specimen only provides information about the tissue contained in the biopsy specimen, such that a biopsy specimen may not generally be used to identify tumor metastasis. Accordingly, the use of histopathology in diagnosing or monitoring tumors, especially metastasized tumors, has many limitations.
Circulating tumor cells (CTCs) can be identified in patients before a tumor is originally detected, and CTCs may play an important factor in early diagnosing cancer. In addition, since cancer may spread through blood, CTCs may be a marker for identifying cancer metastasis. In addition, when CTCs can be detected after a tumor is removed by a surgical operation, the possibility of recurrence of cancer is very high. However, since the amount of CTCs in blood may be very small and since CTCs are very fragile, it is difficult to correctly quantify CTCs. Accordingly, there is a need to develop a diagnosis method with high sensitivity in detecting CTCs, cancer cells, or cancer stem cells present in patients.
Red blood cells, white blood cells/circulating tumor cells, or a serum may be manually separated from a density gradient in order to isolate CTCs, cancer cells, or cancer stem cells. However, a layer of white blood cells/CTCs is very thin, and thus, the layer of white blood cells/CTCs based on the density gradient is difficult to manually separate. Also, separation reproducibility largely depends on the ability of the person performing the separation.